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just-Addict edited this page Jun 24, 2016 · 3 revisions

##Directives

###Scale Directives

Scale directives change the way scaling affects the waveform and which method is used. You can choose between Reaply Gain scaling or Magnitude scaling. For the latter method there are two alternatives to choose from. The first is to choose whether to scale each channel independantly of other present channels, or to scale all channels while maintaining their relative level differences. The second choice is whether or not to scale the waveform in a symetric or asymetric manner.

  • SCALE_REPLAYGAIN scales using the replay gain tag information if present.
  • SCALE_CMAGNITUDE scales each channel independantly from other present channels
  • SCALE_TMAGNITUDE scales all channels in the current track maintaining relative differences
  • ASYMETRIC slightly changes the way both magnitude scaling directives work.

The first will of course use replay gain tags if present. If there is no replay gain info and SCALE_CMAGNITUDE or SCALE_TMAGNITUDE is also enabled the effect falls back to magnitude scaling. When this happens the directive ASYMETRIC controls how magnitude scaling is applied. Magnitude scaling works by looking at a set of values supplied by the component which contain the value of the lowest peak and the value of the highest peak for the current track. To determine the amount of scaling needed it will look at the absolute value of both lowest and highest peak (absolute because the lowest peak value will always be a negative value as a result of the mapping to a -1,1 scale).

With SCALE_CMAGNITUDE these values only apply to the current channel, and with SCALE_TMAGNITUDE the values apply to all channels. Regardless of which of the two magnitude scaling directives is active, when enabling the ASYMETRIC directive the effect will not just look at which of the two absolute peak values is the highest, instead it will take the difference between the two and shifts the zero line down or up so that both upper and lower half of the waveform will go edge-to-edge.

Both the Replay Gain and one Magnitude directive can be enabled at the same time, in this way if Replay Gain data is present this method will take priority over Magnitude scaling. Be advised that by enabling both methods, you may experience inconsistent behavior if your library contains tracks without Replay Gain data and Magnitude scaling becomes active with asymetric scaling enabled.

The below two images show the difference between channel magnitude scaling and track magnitude scaling. From top to bottom the channel order is front left, front right, center, LFE, rear left and rear right.

TRACK_MAGNITUDE_SCALING
Track Magnitude Scaling

CHANNEL_MAGNITUDE_SCALING
Channel Magnitude Scaling

As you can see, with channel magnitude scaling the LFE channel is scaled exaggeratedly. It ain't pretty but at least it shows there is a signal there.

How asymetric scaling influences the waveform is shown in the below two images where the center line is indicated in white.
STANDARD_MAGNITUDE_SCALING
Without asymetric scaling the waveform is zero line lies exactly on the centerline of the window.

ASYMETRIC_MAGNITUDE_SCALING
With asymetric scaling the zero line is adjusted downward below the center line because this track's absolute lowest peek is smaller than the absolute highest peak.

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